Suelen Goularte Carvalhosuelengc@ime.usp.br

Computação Paralela e DistribuídaProfº Alfredo Goldman

Junho/2015

Go is a programming language designed by Google to help solve Google's problems.

What is Go?

And has big problems!

Which (big) problems?

● Hardware is big and the software is big● There are many millions of lines of software● Servers mostly in C++ and lots of Java and Python● Thousands of engineers work on the code● And of course, all this software runs on zillions of

machines.

In short, development at is big, can be slow, and is often

clumsy. But it is effective.

''''

https://talks.golang.org/2012/splash.article

A lot of others people help to bring go from prototype to reality.

Go became a public Open Source project.

https://golang.org/doc/faq#history

2008 2009 20102007

Starts to have adoption by other programmers

Started and built by Robert Griesemer, Rob Pike and Ken Thompson as a part-time project.

History

● Ken Thompson (B, C, Unix, UTF-8) ● Rob Pike (Unix, UTF-8) ● Robert Griesemer (Hotspot, JVM) ...and a few others engineers at Google

Who were the founders?

2013 20142012

Version history

Go 1.4 (December)

Go 1.3 (June)

Go 1 (March)

Go 1.2 (December)

Go 1.1 (May)

https://golang.org/project/

● Eliminate slowness● Eliminate clumsiness● Improve productive ● Maintain (and improve) scale

It was designed by and for people who write, read, debug and maintain large software systems.

Go's purpose is not to do research programming language design.

Go's purpose is to make its designers' programming lives better.

Why Go?

Go is a compiled, concurrent, garbage-collected, statically typed language developed at .

What is Go?

fix, fmt, get, install, list, tool, version, vet.

build compile packages and dependencies

run compile and run Go program

clean remove object files

env print Go environment information

test test packages and benchmarks

Go is a tool for managing Go source code...

Mainly tools:

Others tools:

Who are using today?

https://github.com/golang/go/wiki/GoUsers

❏ Compiled❏ Garbage-collected❏ Has your own runtime❏ Simple syntax❏ Great standard library❏ Cross-platform❏ Object Oriented (without inheritance)❏ Statically and stronger typed❏ Concurrent (goroutines)❏ Closures❏ Explicity dependencies❏ Multiple return values❏ Pointers❏ and so on...

What will you see in Go?

Have not been implemented in favor of efficiency.

❏ Exception handling❏ Inheritance❏ Generics❏ Assert❏ Method overload

What will you not see in Go?

see a bit of code!

Packages

● Each Go program are compound per packages● Programs starts from main package● This example are using the ftm and math packages

$ go run packages.goMy favorite number is 1

● The var instruction declares a list of variables● The type is informed at the end● The var instruction could be in a package or in a function● The var instruction could includes initializers, 1 per variable. In

this case, the type could be ommited because it will be inferred

Variables

$ go run variables.go0 false false false

$ go run variables-with-initiali1 2 true false no!

$ go run constants.goHello world! Happy 3.14 Day! Go rules? true

● Constants are declared like variables but with keyword const● Can not use the syntx :=

Constants

● Inside a function, the short attribution instruction := can be used instead of a var declaration

Short variables declarations

$ go run short-variable-declarations.go1 2 3 true false no!

Functions● Functions could have zero or more arguments● Notice that the type comes after the parameter name,

like variables

$ go run functions.go55

● A function can have multiple return values

Multiple return values

$ go run multiple-results.goworld hello

● Go has just for as looping structure● It is very similar with C or Java code, except for ( )● Start and end declarations can be empty

Looping For

$ go run for.go45

$ go run for-continu1024

$ go run for-is-go-while.go1024

● Semicolon can be removed and you will have while ● for can run forever

Looping "while" and forever

$ go run forever.goprocess took too long

● It is very similar with C or Java code, except for ( )

if Condition

$ go run if.go1.4142135623730951 2i

$ go run switch.goGo runs on nacl.

● It is very similar with C or Java code, except for ( )

Switch Condition

$ go run defer.gohello world

Defer● Postponing the execution of a function until the function returns● The arguments of the deferred calls are evaluated immediately

What more?● Pointer● Struct● Matrix● Slice● Range● Map● Value function● Closures● Method● Interface● Stringer● Error● and a lot of more!!!

http://go-tour-br.appspot.com

$ go run http.go

A web server● It is just simple to build a web server with 15 lines or less!!

Could you belive that???

● To execute a goroutine, just go!

● To send or receive information between the goroutines, use channels

● Use the GOMAXPROCS environment variable to define the amount of threads

Concurrency (goroutines)

$ go run goroutines.gohelloworldhelloworldhelloworldhelloworldhello

● A goroutine is a lightweight thread managed by Go runtime

Goroutines

$ go run channels.go17 -5 12

Channels● Channels are typed's conduit through which you can send and receive

values with the channel operator <-

Unbuffered Channels

http://www.goinggo.net/2014/02/the-nature-of-channels-in-go.html

c := make (chan int)

Buffered Channels

http://www.goinggo.net/2014/02/the-nature-of-channels-in-go.html

c := make (chan int, 10)

Now you are ready to

!

Bibliografia❏ http://golang.org❏ http://go-tour-br.appspot.com/❏ https://tour.golang.org❏ http://www.golangbr.org/❏ https://vimeo.com/49718712❏ http://gophercon.com❏ http://www.infoq.com/br/news/2014/09/go-1-3❏ http://www.casadocodigo.com.br/products/livro-google-go❏ https://pt.wikipedia.org/wiki/Inferno_(sistema_operacional)❏ http://www.grokpodcast.com/series/a-linguagem-go/❏ https://pt.wikipedia.org/wiki/Go_(linguagem_de_programação)❏ https://gobyexample.com❏ http://www.goinggo.net/2014/02/the-nature-of-channels-in-go.html❏ http://www.goinggo.net/2013/09/detecting-race-conditions-with-go.html?m=1❏ https://en.wikipedia.org/wiki/Green_threads❏ http://www.toptal.com/go/go-programming-a-step-by-step-introductory-tutorial

Questions?